1. Field of the Invention
The present invention generally relates to a sensor arrangement and techniques for the detection of analytes. More specifically, the present invention relates to electronic techniques and devices for olfaction type detection/analysis, where the sensor arrangement is wirelessly connected to the processing arrangement which processes the output of the sensor arrangement, and therefore allows the sensor arrangement be hermetically isolated from the processors and/or remotely disposed with respect to the same.
2. Related Art
Techniques and devices for detecting a wide variety of analytes in fluids such as vapors, gases and liquids are known. An “electronic nose” is an instrument used to detect vapors or chemical analytes in gases, solutions, and solids. In certain instances, the electronic nose is used to simulate a mammalian olfactory system. In general, an electronic nose is a system having an array of sensors that are used in conjunction with pattern-recognition algorithms. Using the combination of chemical sensors, which produce a fingerprint of the vapor or gas, the recognition algorithms can identify and/or quantify the analytes of interest. The electronic nose is thus capable of recognizing unknown chemical analytes, odors, and vapors.
In practice, an electronic nose is presented with a substance such as an odor or vapor, and the sensor converts the input of the substance into a response, such as an electrical response. The response is then compared to known responses that have been stored previously. By comparing the unique chemical signature of an unknown substance to “signatures” of known substances, the unknown analyte can be determined. A variety of sensors can be used in electronic noses that respond to various classes of gases and odors.
A wide variety of commercial applications are available for electronic noses including, but not limited to, environmental toxicology and remediation, biomedicine, such as microorganism classification or detection, material quality control, food and agricultural products monitoring, heavy industrial manufacturing, ambient air monitoring, worker protection, emissions control, and product quality testing. Many of these applications require a portable device because they are located in the field or because they are inaccessible with respect to larger laboratory models.
While handheld electronic nose devices are commercially available, they generally require the device to be in close proximity with the analyte. In certain circumstances, where the analyte is potentially a hazardous compound, the requirement of close proximity can potentially expose the operator of such a device to hazardous conditions. While it may be desirable to break up the sensing array subunit from the processing subunit, such an option is difficult to implement, primarily due to the power requirements of the sensor array unit, as well as the need to maintain a direct electrical connection between the sensor array and the remainder of the sensing device.
On the other hand, in an unrelated area of industry, remote, so called “passive” identification has flourished. An implementation of passive identification technology includes radio-frequency tags. Radio-frequency (“RF”) tags have been used by industry for many years. Common uses include identification of rail cars, automobiles, cattle management and salmon returning to spawn in the Columbia River, as well as embedding the tiny tags under the skin of a pet to identify a lost dog or cat. Many people encounter RF tags when a store clerk removes theft-deterring devices from expensive clothing items.
RF and other passive tags have enabled a method of identifying items from a distance, commonly called RFID, or radio frequency identification. RIFD systems generally comprise two components, namely transponders which are attached to the items to be labeled, and readers for reading the identity of the transponders. In some cases the transponders might be programmed to broadcast data representing their identity, while in other cases, it might be an ON/OFF state such as is used in electronic article surveillance systems commonly used for anti-shoplifting in retail stores. RFID systems use small tags that contain information about the object to which the tag is attached. In its simplest form, a radio-frequency tag is a small electronic circuit board. It contains a suitable antenna and/or coil. The tags store data, such as the identification number correlating to an item. The tag being a passive device does not require a battery. A device called an interrogator or a reader is used to read the tags. The interrogator includes another electronic circuit, typically larger than the tag, that contains an antenna and a transceiver. The antenna emits radio waves which are received by the RF tag, and which is energized thereby. The tag transmits its stored, encoded data back to the interrogator wherein it is decoded.
While RFID technology and electronic article surveillance have seen many advances, the tag technology has generally been limited to rather simplistic arrangements which merely issue prestored data in response to an interrogation signal sent by an interrogation unit.
There is, therefore, a need to extend RFID technology to include more intelligent arrangements such as a versatile robust chemical sensing system for obtaining information pertaining to an analyte (e.g. presence, concentration, etc.) in various diverse test samples/environments via a wireless/remote query, without requiring a hardwired connection between the sensing elements and the data processing arrangement.